[PATCH 0/4] ARM: imx6q: clean up board specific CLKO setup

[PATCH 0/4] ARM: imx6q: clean up board specific CLKO setup

[Shawn Guo]

The CLKO is widely used by imx6q board designs to clock audio codec.
Currently, imx6q-sabrelite and imx6qdl-sabresd set up CLKO in board
specific hooks, while imx6qdl-wandboard handles that in U-Boot.
Since most audio codecs accept 24 MHz frequency, the series adds missing
CLKO pieces into clock driver, and initially sets up CLKO with OSC24M
(cko <-- cko2 <-- osc).  Then those board specific CLKO setup for audio
codec can be removed, while it improves the power efficiency@the same
time by saving the use of PLL.

Shawn

Shawn Guo (4):
  ARM: imx6q: add spdif gate clock
  ARM: imx6q: add cko2 clocks
  ARM: imx6q: add the missing cko output selection
  ARM: imx6q: remove board specific CLKO setup

 .../devicetree/bindings/clock/imx6q-clock.txt      |    5 ++
 arch/arm/boot/dts/imx6q-sabrelite.dts              |    2 +-
 arch/arm/boot/dts/imx6qdl-sabresd.dtsi             |    2 +-
 arch/arm/boot/dts/imx6qdl-wandboard.dtsi           |    2 +-
 arch/arm/mach-imx/clk-imx6q.c                      |   30 ++++++++-
 arch/arm/mach-imx/mach-imx6q.c                     |   69 --------------------
 6 files changed, 37 insertions(+), 73 deletions(-)

-- 
1.7.9.5

[PATCH 1/4] ARM: imx6q: add spdif gate clock

[Shawn Guo]

It adds the missing spdif gate clock into imx6q clock driver.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 .../devicetree/bindings/clock/imx6q-clock.txt      |    1 +
 arch/arm/mach-imx/clk-imx6q.c                      |    4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/clock/imx6q-clock.txt b/Documentation/devicetree/bindings/clock/imx6q-clock.txt
index a0e104f..794d089 100644
--- a/Documentation/devicetree/bindings/clock/imx6q-clock.txt
+++ b/Documentation/devicetree/bindings/clock/imx6q-clock.txt
@@ -209,6 +209,7 @@ clocks and IDs.
 	pll5_post_div		194
 	pll5_video_div		195
 	eim_slow      		196
+	spdif      		197
 
 Examples:
 
diff --git a/arch/arm/mach-imx/clk-imx6q.c b/arch/arm/mach-imx/clk-imx6q.c
index db9f8f5..d739df1 100644
--- a/arch/arm/mach-imx/clk-imx6q.c
+++ b/arch/arm/mach-imx/clk-imx6q.c
@@ -239,7 +239,8 @@ enum mx6q_clks {
 	pll4_audio, pll5_video, pll8_mlb, pll7_usb_host, pll6_enet, ssi1_ipg,
 	ssi2_ipg, ssi3_ipg, rom, usbphy1, usbphy2, ldb_di0_div_3_5, ldb_di1_div_3_5,
 	sata_ref, sata_ref_100m, pcie_ref, pcie_ref_125m, enet_ref, usbphy1_gate,
-	usbphy2_gate, pll4_post_div, pll5_post_div, pll5_video_div, eim_slow, clk_max
+	usbphy2_gate, pll4_post_div, pll5_post_div, pll5_video_div, eim_slow,
+	spdif, clk_max
 };
 
 static struct clk *clk[clk_max];
@@ -521,6 +522,7 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
 	clk[sata]         = imx_clk_gate2("sata",          "ipg",               base + 0x7c, 4);
 	clk[sdma]         = imx_clk_gate2("sdma",          "ahb",               base + 0x7c, 6);
 	clk[spba]         = imx_clk_gate2("spba",          "ipg",               base + 0x7c, 12);
+	clk[spdif]        = imx_clk_gate2("spdif",         "spdif_podf",    	base + 0x7c, 14);
 	clk[ssi1_ipg]     = imx_clk_gate2("ssi1_ipg",      "ipg",               base + 0x7c, 18);
 	clk[ssi2_ipg]     = imx_clk_gate2("ssi2_ipg",      "ipg",               base + 0x7c, 20);
 	clk[ssi3_ipg]     = imx_clk_gate2("ssi3_ipg",      "ipg",               base + 0x7c, 22);
-- 
1.7.9.5

[PATCH 2/4] ARM: imx6q: add cko2 clocks

[Shawn Guo]

It adds the missing cko2 clocks, including multiplexer, divider and
gate.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 .../devicetree/bindings/clock/imx6q-clock.txt      |    3 +++
 arch/arm/mach-imx/clk-imx6q.c                      |   15 ++++++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/clock/imx6q-clock.txt b/Documentation/devicetree/bindings/clock/imx6q-clock.txt
index 794d089..c6d7e16 100644
--- a/Documentation/devicetree/bindings/clock/imx6q-clock.txt
+++ b/Documentation/devicetree/bindings/clock/imx6q-clock.txt
@@ -210,6 +210,9 @@ clocks and IDs.
 	pll5_video_div		195
 	eim_slow      		196
 	spdif      		197
+	cko2_sel      		198
+	cko2_podf      		199
+	cko2      		200
 
 Examples:
 
diff --git a/arch/arm/mach-imx/clk-imx6q.c b/arch/arm/mach-imx/clk-imx6q.c
index d739df1..924ed84 100644
--- a/arch/arm/mach-imx/clk-imx6q.c
+++ b/arch/arm/mach-imx/clk-imx6q.c
@@ -206,6 +206,16 @@ static const char *vpu_axi_sels[]	= { "axi", "pll2_pfd2_396m", "pll2_pfd0_352m",
 static const char *cko1_sels[]	= { "pll3_usb_otg", "pll2_bus", "pll1_sys", "pll5_video_div",
 				    "dummy", "axi", "enfc", "ipu1_di0", "ipu1_di1", "ipu2_di0",
 				    "ipu2_di1", "ahb", "ipg", "ipg_per", "ckil", "pll4_post_div", };
+static const char *cko2_sels[] = {
+	"mmdc_ch0_axi", "mmdc_ch1_axi", "usdhc4", "usdhc1",
+	"gpu2d_axi", "dummy", "ecspi_root", "gpu3d_axi",
+	"usdhc3", "dummy", "arm", "ipu1",
+	"ipu2", "vdo_axi", "osc", "gpu2d_core",
+	"gpu3d_core", "usdhc2", "ssi1", "ssi2",
+	"ssi3", "gpu3d_shader", "vpu_axi", "can_root",
+	"ldb_di0", "ldb_di1", "esai", "eim_slow",
+	"uart_serial", "spdif", "asrc", "hsi_tx",
+};
 
 enum mx6q_clks {
 	dummy, ckil, ckih, osc, pll2_pfd0_352m, pll2_pfd1_594m, pll2_pfd2_396m,
@@ -240,7 +250,7 @@ enum mx6q_clks {
 	ssi2_ipg, ssi3_ipg, rom, usbphy1, usbphy2, ldb_di0_div_3_5, ldb_di1_div_3_5,
 	sata_ref, sata_ref_100m, pcie_ref, pcie_ref_125m, enet_ref, usbphy1_gate,
 	usbphy2_gate, pll4_post_div, pll5_post_div, pll5_video_div, eim_slow,
-	spdif, clk_max
+	spdif, cko2_sel, cko2_podf, cko2, clk_max
 };
 
 static struct clk *clk[clk_max];
@@ -398,6 +408,7 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
 	clk[vdo_axi_sel]      = imx_clk_mux("vdo_axi_sel",      base + 0x18, 11, 1, vdo_axi_sels,      ARRAY_SIZE(vdo_axi_sels));
 	clk[vpu_axi_sel]      = imx_clk_mux("vpu_axi_sel",      base + 0x18, 14, 2, vpu_axi_sels,      ARRAY_SIZE(vpu_axi_sels));
 	clk[cko1_sel]         = imx_clk_mux("cko1_sel",         base + 0x60, 0,  4, cko1_sels,         ARRAY_SIZE(cko1_sels));
+	clk[cko2_sel]         = imx_clk_mux("cko2_sel",         base + 0x60, 16, 5, cko2_sels,         ARRAY_SIZE(cko2_sels));
 
 	/*                              name         reg      shift width busy: reg, shift parent_names  num_parents */
 	clk[periph]  = imx_clk_busy_mux("periph",  base + 0x14, 25,  1,   base + 0x48, 5,  periph_sels,  ARRAY_SIZE(periph_sels));
@@ -447,6 +458,7 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
 	clk[emi_slow_podf]    = imx_clk_fixup_divider("emi_slow_podf", "emi_slow_sel",   base + 0x1c, 23, 3, imx_cscmr1_fixup);
 	clk[vpu_axi_podf]     = imx_clk_divider("vpu_axi_podf",     "vpu_axi_sel",       base + 0x24, 25, 3);
 	clk[cko1_podf]        = imx_clk_divider("cko1_podf",        "cko1_sel",          base + 0x60, 4,  3);
+	clk[cko2_podf]        = imx_clk_divider("cko2_podf",        "cko2_sel",          base + 0x60, 21, 3);
 
 	/*                                            name                 parent_name    reg        shift width busy: reg, shift */
 	clk[axi]               = imx_clk_busy_divider("axi",               "axi_sel",     base + 0x14, 16,  3,   base + 0x48, 0);
@@ -537,6 +549,7 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
 	clk[vdo_axi]      = imx_clk_gate2("vdo_axi",       "vdo_axi_sel",       base + 0x80, 12);
 	clk[vpu_axi]      = imx_clk_gate2("vpu_axi",       "vpu_axi_podf",      base + 0x80, 14);
 	clk[cko1]         = imx_clk_gate("cko1",           "cko1_podf",         base + 0x60, 7);
+	clk[cko2]         = imx_clk_gate("cko2",           "cko2_podf",         base + 0x60, 24);
 
 	for (i = 0; i < ARRAY_SIZE(clk); i++)
 		if (IS_ERR(clk[i]))
-- 
1.7.9.5

[PATCH 3/4] ARM: imx6q: add the missing cko output selection

[Shawn Guo]

The clock output on imx6q CCM_CLKO1 pad is not always cko1 clock, and
there is a multiplexer to select between cko1 and cko2.  Add this
missing selection as the clock cko.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 .../devicetree/bindings/clock/imx6q-clock.txt      |    1 +
 arch/arm/mach-imx/clk-imx6q.c                      |    4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/clock/imx6q-clock.txt b/Documentation/devicetree/bindings/clock/imx6q-clock.txt
index c6d7e16..3066f181 100644
--- a/Documentation/devicetree/bindings/clock/imx6q-clock.txt
+++ b/Documentation/devicetree/bindings/clock/imx6q-clock.txt
@@ -213,6 +213,7 @@ clocks and IDs.
 	cko2_sel      		198
 	cko2_podf      		199
 	cko2      		200
+	cko      		201
 
 Examples:
 
diff --git a/arch/arm/mach-imx/clk-imx6q.c b/arch/arm/mach-imx/clk-imx6q.c
index 924ed84..ed19b33 100644
--- a/arch/arm/mach-imx/clk-imx6q.c
+++ b/arch/arm/mach-imx/clk-imx6q.c
@@ -216,6 +216,7 @@ static const char *cko2_sels[] = {
 	"ldb_di0", "ldb_di1", "esai", "eim_slow",
 	"uart_serial", "spdif", "asrc", "hsi_tx",
 };
+static const char *cko_sels[] = { "cko1", "cko2", };
 
 enum mx6q_clks {
 	dummy, ckil, ckih, osc, pll2_pfd0_352m, pll2_pfd1_594m, pll2_pfd2_396m,
@@ -250,7 +251,7 @@ enum mx6q_clks {
 	ssi2_ipg, ssi3_ipg, rom, usbphy1, usbphy2, ldb_di0_div_3_5, ldb_di1_div_3_5,
 	sata_ref, sata_ref_100m, pcie_ref, pcie_ref_125m, enet_ref, usbphy1_gate,
 	usbphy2_gate, pll4_post_div, pll5_post_div, pll5_video_div, eim_slow,
-	spdif, cko2_sel, cko2_podf, cko2, clk_max
+	spdif, cko2_sel, cko2_podf, cko2, cko, clk_max
 };
 
 static struct clk *clk[clk_max];
@@ -409,6 +410,7 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
 	clk[vpu_axi_sel]      = imx_clk_mux("vpu_axi_sel",      base + 0x18, 14, 2, vpu_axi_sels,      ARRAY_SIZE(vpu_axi_sels));
 	clk[cko1_sel]         = imx_clk_mux("cko1_sel",         base + 0x60, 0,  4, cko1_sels,         ARRAY_SIZE(cko1_sels));
 	clk[cko2_sel]         = imx_clk_mux("cko2_sel",         base + 0x60, 16, 5, cko2_sels,         ARRAY_SIZE(cko2_sels));
+	clk[cko]              = imx_clk_mux("cko",              base + 0x60, 8, 1,  cko_sels,          ARRAY_SIZE(cko_sels));
 
 	/*                              name         reg      shift width busy: reg, shift parent_names  num_parents */
 	clk[periph]  = imx_clk_busy_mux("periph",  base + 0x14, 25,  1,   base + 0x48, 5,  periph_sels,  ARRAY_SIZE(periph_sels));
-- 
1.7.9.5

[PATCH 4/4] ARM: imx6q: remove board specific CLKO setup

[Shawn Guo]

The CLKO is widely used by imx6q board designs to clock audio codec.
Since most codecs accept 24 MHz frequency, let's initially set up CLKO
with OSC24M (cko <-- cko2 <-- osc).  Then those board specific CLKO
setup for audio codec can be removed.

The board dts files also need an update on cko reference in codec node.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 arch/arm/boot/dts/imx6q-sabrelite.dts    |    2 +-
 arch/arm/boot/dts/imx6qdl-sabresd.dtsi   |    2 +-
 arch/arm/boot/dts/imx6qdl-wandboard.dtsi |    2 +-
 arch/arm/mach-imx/clk-imx6q.c            |   11 +++++
 arch/arm/mach-imx/mach-imx6q.c           |   69 ------------------------------
 5 files changed, 14 insertions(+), 72 deletions(-)

diff --git a/arch/arm/boot/dts/imx6q-sabrelite.dts b/arch/arm/boot/dts/imx6q-sabrelite.dts
index e0f4cd0..3530280 100644
--- a/arch/arm/boot/dts/imx6q-sabrelite.dts
+++ b/arch/arm/boot/dts/imx6q-sabrelite.dts
@@ -167,7 +167,7 @@
 	codec: sgtl5000 at 0a {
 		compatible = "fsl,sgtl5000";
 		reg = <0x0a>;
-		clocks = <&clks 169>;
+		clocks = <&clks 201>;
 		VDDA-supply = <&reg_2p5v>;
 		VDDIO-supply = <&reg_3p3v>;
 	};
diff --git a/arch/arm/boot/dts/imx6qdl-sabresd.dtsi b/arch/arm/boot/dts/imx6qdl-sabresd.dtsi
index 166b9ae..75b36b2 100644
--- a/arch/arm/boot/dts/imx6qdl-sabresd.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-sabresd.dtsi
@@ -109,7 +109,7 @@
 	codec: wm8962 at 1a {
 		compatible = "wlf,wm8962";
 		reg = <0x1a>;
-		clocks = <&clks 169>;
+		clocks = <&clks 201>;
 		DCVDD-supply = <&reg_audio>;
 		DBVDD-supply = <&reg_audio>;
 		AVDD-supply = <&reg_audio>;
diff --git a/arch/arm/boot/dts/imx6qdl-wandboard.dtsi b/arch/arm/boot/dts/imx6qdl-wandboard.dtsi
index 7a46f64..77188cb 100644
--- a/arch/arm/boot/dts/imx6qdl-wandboard.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-wandboard.dtsi
@@ -60,7 +60,7 @@
 	codec: sgtl5000 at 0a {
 		compatible = "fsl,sgtl5000";
 		reg = <0x0a>;
-		clocks = <&clks 169>;
+		clocks = <&clks 201>;
 		VDDA-supply = <&reg_2p5v>;
 		VDDIO-supply = <&reg_3p3v>;
 	};
diff --git a/arch/arm/mach-imx/clk-imx6q.c b/arch/arm/mach-imx/clk-imx6q.c
index ed19b33..97f2702 100644
--- a/arch/arm/mach-imx/clk-imx6q.c
+++ b/arch/arm/mach-imx/clk-imx6q.c
@@ -288,6 +288,7 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
 	struct device_node *np;
 	void __iomem *base;
 	int i, irq;
+	int ret;
 
 	clk[dummy] = imx_clk_fixed("dummy", 0);
 	clk[ckil] = imx_obtain_fixed_clock("ckil", 0);
@@ -591,6 +592,16 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
 		clk_prepare_enable(clk[usbphy2_gate]);
 	}
 
+	/*
+	 * Let's initially set up CLKO with OSC24M, since this configuration
+	 * is widely used by imx6q board designs to clock audio codec.
+	 */
+	ret = clk_set_parent(clk[cko2_sel], clk[osc]);
+	if (!ret)
+		ret = clk_set_parent(clk[cko], clk[cko2]);
+	if (ret)
+		pr_warn("failed to set up CLKO: %d\n", ret);
+
 	/* Set initial power mode */
 	imx6q_set_lpm(WAIT_CLOCKED);
 
diff --git a/arch/arm/mach-imx/mach-imx6q.c b/arch/arm/mach-imx/mach-imx6q.c
index 9f06cc8..2460d49 100644
--- a/arch/arm/mach-imx/mach-imx6q.c
+++ b/arch/arm/mach-imx/mach-imx6q.c
@@ -159,30 +159,6 @@ static int ar8031_phy_fixup(struct phy_device *dev)
 	return 0;
 }
 
-static void __init imx6q_sabrelite_cko1_setup(void)
-{
-	struct clk *cko1_sel, *ahb, *cko1;
-	unsigned long rate;
-
-	cko1_sel = clk_get_sys(NULL, "cko1_sel");
-	ahb = clk_get_sys(NULL, "ahb");
-	cko1 = clk_get_sys(NULL, "cko1");
-	if (IS_ERR(cko1_sel) || IS_ERR(ahb) || IS_ERR(cko1)) {
-		pr_err("cko1 setup failed!\n");
-		goto put_clk;
-	}
-	clk_set_parent(cko1_sel, ahb);
-	rate = clk_round_rate(cko1, 16000000);
-	clk_set_rate(cko1, rate);
-put_clk:
-	if (!IS_ERR(cko1_sel))
-		clk_put(cko1_sel);
-	if (!IS_ERR(ahb))
-		clk_put(ahb);
-	if (!IS_ERR(cko1))
-		clk_put(cko1);
-}
-
 #define PHY_ID_AR8031	0x004dd074
 
 static void __init imx6q_enet_phy_init(void)
@@ -197,45 +173,6 @@ static void __init imx6q_enet_phy_init(void)
 	}
 }
 
-static void __init imx6q_sabresd_cko1_setup(void)
-{
-	struct clk *cko1_sel, *pll4, *pll4_post, *cko1;
-	unsigned long rate;
-
-	cko1_sel = clk_get_sys(NULL, "cko1_sel");
-	pll4 = clk_get_sys(NULL, "pll4_audio");
-	pll4_post = clk_get_sys(NULL, "pll4_post_div");
-	cko1 = clk_get_sys(NULL, "cko1");
-	if (IS_ERR(cko1_sel) || IS_ERR(pll4)
-			|| IS_ERR(pll4_post) || IS_ERR(cko1)) {
-		pr_err("cko1 setup failed!\n");
-		goto put_clk;
-	}
-	/*
-	 * Setting pll4 at 768MHz (24MHz * 32)
-	 * So its child clock can get 24MHz easily
-	 */
-	clk_set_rate(pll4, 768000000);
-
-	clk_set_parent(cko1_sel, pll4_post);
-	rate = clk_round_rate(cko1, 24000000);
-	clk_set_rate(cko1, rate);
-put_clk:
-	if (!IS_ERR(cko1_sel))
-		clk_put(cko1_sel);
-	if (!IS_ERR(pll4_post))
-		clk_put(pll4_post);
-	if (!IS_ERR(pll4))
-		clk_put(pll4);
-	if (!IS_ERR(cko1))
-		clk_put(cko1);
-}
-
-static void __init imx6q_sabresd_init(void)
-{
-	imx6q_sabresd_cko1_setup();
-}
-
 static void __init imx6q_1588_init(void)
 {
 	struct regmap *gpr;
@@ -256,12 +193,6 @@ static void __init imx6q_usb_init(void)
 
 static void __init imx6q_init_machine(void)
 {
-	if (of_machine_is_compatible("fsl,imx6q-sabrelite"))
-		imx6q_sabrelite_cko1_setup();
-	else if (of_machine_is_compatible("fsl,imx6q-sabresd") ||
-			of_machine_is_compatible("fsl,imx6dl-sabresd"))
-		imx6q_sabresd_init();
-
 	imx6q_enet_phy_init();
 
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
-- 
1.7.9.5

[PATCH 4/4] ARM: imx6q: remove board specific CLKO setup

[Sascha Hauer]

On Thu, Jul 18, 2013 at 03:31:10PM +0800, Shawn Guo wrote:
> The CLKO is widely used by imx6q board designs to clock audio codec.
> Since most codecs accept 24 MHz frequency, let's initially set up CLKO
> with OSC24M (cko <-- cko2 <-- osc).  Then those board specific CLKO
> setup for audio codec can be removed.
> 
> The board dts files also need an update on cko reference in codec node.
> 
> +	/*
> +	 * Let's initially set up CLKO with OSC24M, since this configuration
> +	 * is widely used by imx6q board designs to clock audio codec.
> +	 */
> +	ret = clk_set_parent(clk[cko2_sel], clk[osc]);
> +	if (!ret)
> +		ret = clk_set_parent(clk[cko], clk[cko2]);
> +	if (ret)
> +		pr_warn("failed to set up CLKO: %d\n", ret);


I don't really like that the clock setup code fiddles with clocks it has
no knowledge about just because it happens to be correct for several
boards.

I currently have no example where this bites me, so I think I can live
with it for now. I just wonder what I should do when this clock is used
for something vital to the system (clocking an FPGA for example?).

Sascha

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[PATCH 4/4] ARM: imx6q: remove board specific CLKO setup

[Shawn Guo]

On Thu, Jul 18, 2013 at 10:36:03AM +0200, Sascha Hauer wrote:
> On Thu, Jul 18, 2013 at 03:31:10PM +0800, Shawn Guo wrote:
> > The CLKO is widely used by imx6q board designs to clock audio codec.
> > Since most codecs accept 24 MHz frequency, let's initially set up CLKO
> > with OSC24M (cko <-- cko2 <-- osc).  Then those board specific CLKO
> > setup for audio codec can be removed.
> > 
> > The board dts files also need an update on cko reference in codec node.
> > 
> > +	/*
> > +	 * Let's initially set up CLKO with OSC24M, since this configuration
> > +	 * is widely used by imx6q board designs to clock audio codec.
> > +	 */
> > +	ret = clk_set_parent(clk[cko2_sel], clk[osc]);
> > +	if (!ret)
> > +		ret = clk_set_parent(clk[cko], clk[cko2]);
> > +	if (ret)
> > +		pr_warn("failed to set up CLKO: %d\n", ret);
> 
> 
> I don't really like that the clock setup code fiddles with clocks it has
> no knowledge about just because it happens to be correct for several
> boards.

I have to admit it's not the best way to handle it, and I can understand
your concern.  What I like about it is we can remove those board
specific hooks from mach-imx6q.c at least for now.

> 
> I currently have no example where this bites me, so I think I can live
> with it for now. I just wonder what I should do when this clock is used
> for something vital to the system (clocking an FPGA for example?).

Go back to set up CLKO in mach-imx6q.c with board specific hook for the
system?

I think I chose to change the default CLKO setup for audio use case, as
all the users we've seen so far is audio codec.  I can still have this
setup done in mach-imx6q.c with of_machine_is_compatible() check on all
those board.  But that also means we need to register lookups for those
CLKO clocks and call clk_get_sys() to get them.

Shawn